SITE INFORMATION AND CORRESPONDENCE

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WASTE DISCHARGE REQUMENTS . -2- , STOCKTON COGENERATICWCOMPANY SAN JOAQUIN COUNTY 5. The Report of Waste Discharge, as well as recent monitoring reports, describe the discharge as follows: Daily Maximum Flow: 1.073 million gallons per day (mgd) Average Temperature: 69°F Constituent Daily max mg/1) Oil and Grease 6.0 COD 24 TSS 18 TOC 1.3 Chlorine Residual 0.06 Arsenic 0.028 Copper 0.05 Molybdenum 0.015 Total Dissolved Solids 1000 6. For discharges to surface water, the Discharger requested in their Report of Waste Discharge dated 23 November 1999 an increase in the maximum allowable discharge flow to 1.3 mgd from the 0.9 mgd in their previous WDRs (Order No. 95-148). In evaluating such a request the Board must consider anti-degradation pursuant to 40 CFR 131.12 and SWRCB Resolution No. 68-16. Historical effluent data finds the quality of the effluent to be better than downstream receiving waters and dissolved oxygen to be higher than both the receiving water and applicable Basin Plan water quality objectives. These are considered benefits to the receiving water. Also, constituents for which the Discharger has permanent or interim effluent limits as part of Section B. Effluent Limitations are not bioaccumulative nor are they responsible for downstream impairment or 303(d) listing. Based on these findings the Board finds that the proposed increase in the maximum allowable discharge will have an insignificant impact on beneficial uses and is therefore acceptable. 7. For discharges to land, the Board has considered anti-degradation pursuant to State Board Resolution No. 68-16 and finds that not enough data exists to determine whether this discharge is consistent with those provisions. Therefore, this Order provides a schedule for data collection to determine whether the discharge will cause an increase in groundwater constituents above that of background levels. If the discharge is causing such an increase, then the Discharger may be required to cease the discharge, implement source control, change the method of disposal, or take other action to prevent groundwater degradation. 8. The U.S. Environmental Protection Agency (EPA) and the Board have classified this discharge as a minor discharge. 9. The Board adopted a Water Quality Control Plan Fourth Edition,for the Sacramento and San Joaquin River Basins, (hereafter Basin Plan). The Basin Plan designates beneficial uses, establishes water quality objectives, and contains implementation programs and policies to achieve